Since the middle of the last century numerous investigations have sought alternative technologies for the production of fuels from renewable sources or industrial waste.
Transesterification or alcoholysis emerged as a significantly-advantageous procedure to make viable the obtainment of fuels from triglycerides, for example those present in vegetable oils.
Transesterification with methanol or ethanol however presents problems. The need to transport and handle large quantities of the said consumables requires excessively-high investment in construction and maintenance of safe plants, principally due to the high risks of poisoning and fire. In addition the burning of fuel produced through alcoholic transesterification of triglycerides generates considerable quantities of formaldehyde, acrolein and benzene which, in addition to being pollutants, cause damage to pistons and engines.
In FCC units the difficulty of producing diesel oil of good quality from vegetable oils mixed into the conventional charge arises from the very high reaction temperatures, never lower than 490° C. In addition the volume of vegetable oil available for the production of diesel oil is very small in relation to the volume of gas oil currently processed. In comparison with the transesterification process, the high investment cost makes the construction of an FCCU (FCC Unit) for exclusive vegetable-oil processing unviable. Nevertheless this alternative route for production of diesel based on the utilisation of seeds of oleaginous plants could be implemented in a refinery the FCCU whereof possesses at least two reactors already in existence.